1. Field of the Invention
The present invention relates to a battery provided with terminals, and more particularly, to a battery provided with terminals, capable of being attached to a circuit board of an electronic apparatus without soldering.
2. Description of the Related Art
In a flat battery such as button-shaped and coin-shaped batteries, or square and cylindrical batteries, a primary battery and a secondary battery represented by an alkaline dry battery, a lithium battery, a lithium secondary battery, and an alkaline storage battery are widely used as main power sources, or backup power supplies for memories of various electronic apparatuses.
When mounting the battery on a circuit board of an electronic apparatus, it is suggested that terminals for soldering a battery to the circuit board, should be attached to the battery and that the battery is soldered to the circuit board together with other electronic parts by means of a reflow soldering furnace, in order to improve the efficiency of a manufacturing process.
However, since the battery may be subjected to a high temperature, for example, over 150.degree. C. when the battery is passed through the reflow soldering furnace and heated, even for a short time, a physical change or chemical change occurs in the structure members of the battery, resulting in deterioration of the sealing characteristic, the discharge characteristic, and the cycle characteristic of the battery, which causes a short circuit in the battery. On the other hand, manual soldering application to the batteries, excluding other electronic parts in order to protect the battery, causes significant deterioration of work efficiency. Thus, there is required a high heat resistant battery, whose characteristics are not affected even though the battery passes through the reflow furnace. In particular, a dire need exists to develop a technology for making a high heat resistant lithium battery in which metal lithium with a low melting point is used for a negative electrode and an organic solvent with high volatility is used as an electrolyte solvent.
In order to complete such a need, batteries which use a high heat resistant packing or an additive for improving a storage characteristic at a high temperature, are proposed (Japanese Unexamined Patent Application Publication Tokkai Nos. 8-153500 and 2000-323171). It is possible to improve the heat resistance of a battery by employing the above structure of the battery. Thus, it is possible to obtain a battery capable of passing through the reflow furnace without being damaged.
In addition to, there is proposed a mounting structure for a battery in which the battery is fixed to a circuit board by interposing the circuit board between a battery body and terminals mounted on the battery body instead of methods for fixing the battery to the circuit board by soldering, which enables the battery to be easily exchanged and repaired (Japanese Unexamined Patent Application Publication No. 10-64490). In accordance with the above method, it is possible to mount the battery on the circuit board without soldering.
However, it has been proven that to make the battery heat resistant causes the following problems. That is, in the former two cases where the packing of the battery is made of a heat resistant material in order to prevent the battery from being damaged when passing through the reflow furnace, the cost of the material significantly increases compared to a material, such as polyolefin, commonly used in a conventional technology. In a case where an additive is included in an electrolyte, since the discharge characteristic of a battery deteriorates more or less, usable electronic apparatuses are restricted. Furthermore, since other structure members should be made of a high heat resistant material even though the additive is added, the cost of the material significantly increases. Since it is required to reduce the amount of the solder used in order to protect the environments due to influences of lead included in solder on environments, it is not preferable to use soldering to conductively connect a battery to a circuit board.
Furthermore, when using the mounting structure in which the circuit board is interposed between the battery body and the terminal mounted on the battery body, since the outer body of the battery directly contacts the conductive portion of the circuit board, the arrangement of the battery is significantly restricted during the mounting of the battery. Thus, it is difficult to compose thin electronic apparatuses and to save the space of the circuit, and it is easy to generate poor connections caused by vibration. Therefore, reliability deteriorates.